1. Field of the Invention
The hardover protection systems and methods are in the field of aircraft flight control systems. More specifically, the hardover protection systems and methods are in the field of control algorithms for fly-by-wire aircraft flight controls and control surfaces such as spoilers, ailerons, and other control surfaces.
2. Description of the Related Art
Unintended deflections of aircraft control surfaces may lead to undesirable aircraft movement, and sometimes catastrophic loss of control of the aircraft. The unintended deflections, sometimes known as hardover events, may be caused by actuator malfunction, disconnection of control cables or actuators, or other system failures. In some hardover events, control surfaces may be jammed or immobilized in the fully deflected position. Safe aircraft operation requires systems and methods of counteracting hardover events to prevent loss of control and potential crash of the aircraft.
In some existing systems, several smaller control surface panels are used so that a failure of one control surface panel will have a lesser impact on the aircraft movement and control. The multiple panels require additional actuators and lead to added complexity and expense.
Many existing systems for detecting and counteracting hardover protection in fly-by-wire aircraft use surface position monitoring or disconnect detection devices and methods to determine when a control surface is jammed, disconnected or in a hardover condition. Some existing systems utilize two actuators per control surface to prevent hardover or disconnect events. These devices and methods add significant complexity to the control systems for the aircraft. The additional complexity adds expense and additional potential for failure of the sensors and systems used by the hardover detection system.
The systems and methods for protecting against control surface hardover and disconnection described herein do not require additional sensors or devices to measure the deflection of the aircraft control surfaces or to detect control surfaces disconnection. Utilizing additional control law algorithms for standard aircraft control surfaces, the described invention provides automatic systems and methods for counteracting undesired aircraft movement caused by control surface failures. As a result, larger control surface panels may be provided on an aircraft using the described systems and methods, thus further reducing the required number of actuators.